1. Field of the Invention
The present invention relates generally to hinges and, more specifically, to a closures mechanism for a door actuated during a fire, which causes the door to automatically close. The present invention provides a hinge with opposing hinge plates comprising door leaf and frame leaf pivotal about their respective aligned knuckles that form housing for a rotationally tensioned spring having a knuckle staked tensioning pin straddling the spring on one end and a composite pin on the other end. The composite pin consists of a pair of superjacent pin members having engageable nubs with one pin member knuckle staked and the other straddling the spring is knuckle anchored by a locking pin and fusible block. When stacked together, the locking pin is above the surface of the hinge pin locking the hinge pin and spring under tension. Exceeding a predetermined temperature the fusible block melts allowing the locking pin to displace the liquid metal which releases the anchored pin member of the composite pin that under the aforementioned spring pressure causes its nub to engage the other composite pin member nub forcing the hinged leaves to an engaging closed position thereby forming a hinge for a door that under ambient temperature freely stays in a desired open state until the fusible block ruptures when acted upon by a predetermined temperature, such as through fire, forcing the door to its closed position by virtue of the rotationally tensioned spring's kinetic energy.
2. Description of the Prior Art
There are no known door hinges incorporating fusible blocks that will cause an unattended door to close in case of fire. Since a closed door will inhibit the spread of fire through a structure, it is felt that a need exists for a mechanism that will automatically close a door when a fusible block is ruptured.